Gauge



Feb. 21, 1933. NELSON 1,898,257.

GAUGE Filed Jan. 4, 1930 Patented Feb. 21, 191:3 I I UNITED STATESPATENT orrlcE Application filed January 4, 1980. Serial No. 418,518.

This invention relates generally to indi- Fig.2isalongitudinal sectionalview showcating devices, and more particularly to ing a portion of thegauge stem onan enpressure indicating gauges of the type having largedscale;

a flexible pressure responsive element. Fig. 3 is a longitudinalsectional View 5. Gauges of this type now being extensively showinganotherform of gauge stem; and 55 used employ a Bourdon tube as aflexible Fig. 4 'is a longitudinal sectional view element. Frequentlythese gauges are used showing still another form of gauge stem. on pipelines or chambers in which pressures In the drawing illustrating myinvention, fluctuate rapidly or violently, as, for ex- I have shownapressure gauge of the type 0 ample, passages or chambers connected tohaving a flexible tubular pressure'responsive the discharge side ofcertain pumps and to element 11 commonly known as a Bourdon hydraulicaccumulators. These rapid or viotube. This element is housed within thelent fluctuations or pulsations in the pressure casing l2 and issupported on the-inner end medium cause corresponding vibrations or ofthe gauge stem 13 which maybe secured 15 deflections of theflexibleelement, with the to the casing in any desired manner, as by result thatthese elements soon fail. These means of screws A dial 15 is suitablydeflections of the pressure responsive element supported and is providedwith a scale repre-, also subject other parts of the gauge to wearsenting various pressure values. A movable and, in addition, make thereading of prespointer 16 is connected by suitable linkage 17 20 sureindications very diflicult. to the free end of the pressure responsiveDuring use of pressure gauges of this type, ,selement so thatdeflections of this element in the Bourdon tubeelements are frequentlyresponse to pressure changes will be visually subjected to overloads bypressure increases indicated in awell known manner. in the externalmedium above the pressure A passage 18 extending axially within-the 5values for which the gauges are intended.' gauge stem communicates withthe interior When thus overloaded, the pressure res 'on-- of thepressure responsive element so as to sive element may be deflected'beyon its transmlt pressure to this element from an exelastic limit andits'accuracy and usefulness ternal pressure medium. The passage 18 anddestroyed. thepressure responsive element are filled with It istherefore an object of this invention asuitable substance, such asoil orother liquid, to provide an improved and more durable through which .thepressure is transmitted form'bf indicating device which will give fromthe external pressure medium to the accurate indications. interior ofthe pressure responsive element.

Another object of this invention is to pr'o- Thisbody ofliquid may beretained within the vide an indicating device having com act passage andthe element connected thereto by and simplified means for dampening viraanysuitablemeanswhichwill permit pressures tions of the parts. 1 to bereadily transmitted from the external A further object of this inventionis to medium to the pressure responsive element.

40 provide an indicating device having means In Fig. 2 of the drawing,I'have shown as for protecting the pressure responsive elesuch means aplunger 19 slidably mounted ment against overload. in the lower portionof the assa e 18. 'This The invention may be further briefly sumplungerretalns the body of iiqui within the marized as consisting in certainnovel compassage and separates the liquid from the exbinations andarrangements of parts hereinternal pressure medium. For normallymainafter described and particularly set out in taining the plunger inproper position with the appended claims. Y respect to the body ofliquid retained in the In the accompanying sheet of drawing, device, Iprovide a coil spring 20 having one 7 Figure 1 is a front elevationalview, with end connected to theplunger and the other 50 parts brokenaway, showing a pressure gauge end thereof attached to a pin 21 mountedin embodying my invention; the stem so asto extend across the passage18. At atmospheric pressure; this spring normally holds the plunger inproper place, but when changes occur in the external pressure medium,the spring permits sliding movement of the plunger.

I have found that objectionable vibrations of the pressure responsiveelement can be prevented if sudden pressure changes in the externalmedium can be transmitted to the pressure responsive element in such away as to make these pressure changes be felt gradually within thiselement. To accomplish this result, I provide a restriction 22 in thepassage 18. This restriction may 'be formed during the drilling of thestem by leaving a wall of material 23 between upper and lower portionsof the passage 18. Obviously, however, this restriction could be aseparate part pressed into orotherwise secured in this passage. Theopening 24 of the restriction is of greatly reduced area in comparisonwith the area of the passage 18, and I have found that best results are..obtained when the area of this passage is substantially proportioned tothe viscosity of the liquid retained in the passage: That is to say,when a limpid fluid, such as water, is used in the passage, the area ofthe opening 24 must be very small to produce the desired dampeningeffect. When a more viscous fluid is used, such as oil, theopening 24must be made of correspondingly larger area. To more fully appreciatethe dampening effect produced by the restriction 22, it is pointed outthat for a limpid fluid, such as water, 'I contemplate making theopening 24 approximately fivethousandths of an inch in diameter.However, in determining the size of the restricted opening and theviscosity of the fluid to be used therewith in a gauge for a particularduty, the degreeof pressure change and the violence or suddenness of thepressure change in the external medium, are factors which would be takeninto consideration because the rate at which the liquid will flowthrough the restricted openin is dependent upon such factors as the size0 the restricted opening,

the viscosity of the fluid, the degree of pressure change andtheviolence ofthe pressure change.

When anincrease in pressure occurs in the external medium, the forceapplied to the plunger 19 causes some of the body of fluid in thepassage 18 to be forced through the opening of the restriction 22, thuscausing the pressure responsive element to be correspondingly deflected.When a decrease in pressure occurs in the external medium, the flexiblepressure responsive element forces some of the liquid back through theopening of the restriction. The transfer of some of the body of liquidthrough the opening 24 takes place gradually because of the greatlyreduced area of this opening. The gradual transfer of fluid through thisreduced opening,

causes pressure changes to be felt gradually within the pressureresponsive element and this dampening or throttling effect prevents thepressure responsive element from being vibrated in response to rapid orviolentfluctuations in the pressure of the external medium.

In Fig. 3 of the drawing 1 show an arrangement which is somewhat similarto the arrangement shown inFig. 2. In this arrangement the stem 34 isprovided with a passage 35having arestriction 36 therein. Below therestriction 36 the wall of the passage 35 is. rovided with an annularinclined shoulder 3 which forms a stop for limiting the movement of theplunger 38. The upper end of the plunger is provided with a taperedportion 39 which seats against the annular shoulder 37 when the plug hasbeen moved by the pressure of the external medium having reachedafpredetermined value.

In moving into engagement with the annular shoulder 37, the plunger 38displaces a definite volume of the body of liquid 38 confined in thepassage and forces this volume into the pressure responsive element. Theparts of the device are so proportioned that when this displaced volumeof liquid has been forced into the pressure responsive element thelatter will be deflected an amount corresponding with the maximumpressure indication for which the gauge is intended. The seat ing of theplunger prevents more than the predetermined, definite volume of fluidfrom entering the pressure responsive element, so that by limiting theextent of movement of the plunger 38 an'abnormally large increase inpressure in the external medium will not be transmitted to the pressureresponsive element. If the abnormal pressure of the external mediumcontinues for a prolonged interval of time, the plunger is'held seatedby the pressure during such interval. This element is thus protectedfrom being distorted beyond its elastic limit by abnormal increases inpressure, and is rotected from overload for the duration of the abnormalpressure condition.

' For normally holding the plunger in proper position within thepassage, I provide a coil spring 40 having one end connected 'to theplunger38 and the other end connected to a pin 41 mounted in the wallsof the stem and extending across the passage.

The pressure medium, with which gauges of this type are sometimes used,may contain foreign particles which might adhere to the walls of thelower portion of the passages 18 and 35, shown in Figs. 2 and 3respectively, and prevent free movement of the plungers mounted in thesepassages. To prevent foreign matter from entering these passages, and toprovide means for retaining the liquid within the passages duringshipment or storage "of the gauges, it may be advisable to provide aflexible diaphragm across the t inter? 5 struction a stem 42 is providedwith a'passage 43 having a restriction 44 therein. Below the restrictionthe wall of the passage is formed with an inclined annular shoulder 45which forms a stop for limiting the movement of the plunger 46 in themanner already described in connection with Fig. 3. A spring 47 havingone end thereof secured to the pin 48 and its other end secured to theplunger retains the latter in proper position atvzero cent the lower endof the stem so as to close the passage 43. The diaphragm prevents escapeof the body of liquid 50 and prevents 'forei n matter from entering thepassage and ering with the movement of the plunger. j

It will now be readily seen that I have provided a form of pressuregauge having simple, compact, and eflicient' means for preventingfluctuations or vibfationsvof the pressure responsive element inresponse to ra id or violent pressure'changes occurring in t e externalmedium. It will also be readily seen .that I have provided novel meansfor proment from being distorted beyond its elastic limit by abnormalincreases-in the pressure of the external medium. j Y

In disclosing my invention I have referred to a pressure gauge having aBourbon tube type of pressure responsive element, however, it should beunderstood that the principles of my'invention may also be embodied ingauges employing pressure responsive elements of other forms. Likewise,while I have shown a auge having only one pressure'responsiveedementmbviously my invention may be applied to gauges havin more thanone of these elements such as di erential gauges.

While I have shown and described the device of my invention in adetailed manner, it

.should be understood, however, thatI do not intend to limit 111 self tothe precise details shown and descri d, but regard my invenuid from saidexternal medium, and means for pressure. A diaphragm 49 is mounted adjatectihg the flexible pressure responsive ele- I tion as including suchchanges and modifilimiting the movement of said member to protect' saidelement against overload.

v 2. In an indicating'device, the combination of a pressure responsiveelement, means for visibly indicating deflections of said element,

a body having a passage communicating with said element, a body ofliquid in said element and said passa e for transmitting pressure tosaid element om an external medlum, a

plunger slidable axially in said passage and separating said bod ofliquid from said external medium, an means for limiting the movement ofsaid plunger to protect said element against overload.

3. In an indicating device, the combination of a pressureresponsive-element, means for visibly indicating deflections of saidelement, a body having a passage communicating with said element, a bodyoiliquid in said passage and said element, means restricting themovement of liquid in said passage, a slidable plunger in said passageseparating said body ofliquid from-an external medium, and means fornormally holding said plupger in place at atmospheric pressure. 7 I

4. In an mdicating device, the combination of a pressure responsiveelement, means for visibly indicating deflections of said element, l

a body having a passage communicating with said element, abody of liquidin said element and said passage for transmitting pressure to saidelement from an external medium, a

I an external medium, the area ofsaid opening being substantiallyproportioned to the vis-' co sity of said liquid, a movable memberseparating said body of liquid from said external medium, and means forlimiting the movement of said member to protect said element againstoverload.

6. In an indicating device, the combination of a pressure responsiveelement, means for indicating deflections of said element, a body havinga passage communicating with said element, a restriction in said passagehaving an'opening therethrou h of reduced area, a body'of liquid in saipassage for transmitting pressure to said element from an externalmedium, the area of said opening beingsubstantially proportioned to theviscosity of said liquid, a movable member separating said body ofliquid from said external medium, means for normally holding said memberin place at atmospheric pressure, and

movable member separating said body of means for limiting the movementof said ineiiber to protect said element against over- 7 In anindicating device, the combination of a pressure responsive element,means for visibly indicating deflections of said element,

a body having a passage communicating with said element, fluid in saidpassage for transmitting pressure to said element from an ex- 10 ternalmedium, and means for closing said passage when a predetermined volumeof said fluid has been forced into said element by the pressure of saidexternal medium.

8. In an indicating device, the combination of. a pressure responsiveelement, means fot visibly indicating deflections of said element, abody having a passage communicating with said element, a body of liquidin said element and said passage for transmitting pressure to theelement from an external medium,'a member movable in said passage incontact with said liquid, means for limiting the movement of said memberto protect said element against overload, and flexible means sealingsaid passage to confine said liquid therein.

9. In an indicating device, the combination of a pressure responsiveelement, means for visibly indicating deflections of said element, abody having a passage communicating with said element, a body of liquidin said element and said passage for transmitting pressure to theelement from an external medium, a plunger slidable axially in saidpassage in contact with said li uid, means for limiting the movement ofsai plunger to protect said element against overload, means normallypositioning said plunger in said passage with respect to said limitingmeans, and flexible means sealing said passage to confine said 40 liquidtherein.

In testimony whereof, I hereunto aflix my signature.

, RALPH M. NELSOQT

